Had a few general questions asking about this, so here's my take from many I've fixed over the years. If there's one thing associated with injector MOSFET failures on 2007 (and only 2007) cars, it's misfires. A bad coil can cause it, running on an empty tank of fuel, old plugs, dirty intake valves etc. One thing that causes misfires, is bad injectors. OP had bad injectors, he pulled his plugs and had a few that were black and fouled. That's always an injector. An injector spraying poorly is asking for a miss, easily killing the defective MOSFETs in the MSD80.
Fix is to replace all the MOSFETs with upgraded parts from Fairchild that handle more voltage. Not just the bad one. They don't ALWAYS fail open, just usually, voltage can just as easily damage the gate as short it. The DME also has checks for these so it's best they all match. Whatever OP had his replaced with, was one I hadn't seen before. The datasheet for it was rated lower than OEM in a few places, not ideal, and it was dissimilar from the others. I wasn't 100% sure it was the cause as I've never seen this done, I always do all 6 with upgraded parts (also didn't want to drive an hour my day off this month to solder, I don't get many).
The fact is his car lasted to 9X,XXX miles and 10 years with index 5 injectors without having a failure while being modified. That DME deserves a trophy. Tune a car, blow a MOSFET. Swap to e85, MOSFET. Low on gas, MOSFET. Hell you replace a battery and the next day the MOSFETs fail. Welcome to MSD80. It's an easy fix/upgrade so do it right and get the upgraded Fairchild part or migrate to MSD81, or you'll have a headache.